I've always been impressed how much of the fervent discussion on voter fraud is designed to make people stoooopid.
You can't vote twice. Your vote, and your signature, is checked against the voter roll. If you sign in in person, then your mail in is discarded. To flood in illegal votes you need to know names, need to know their signature, and know they didn't vote already as just a start. You can't vote in person in a precinct that you're not registered in.
So these people blathering on saying "fraud, so my guy won" is classic third world dictator tactics (delegitimize the election by screaming about rigging and fraud prior, try to fuck up the vote, cry fraud afterward and fight it out on the street to take power). Keep in mind also that the recounts almost always, when they did show a minor change, showed a shift toward Biden. Also keep in mind Biden was polling 7 points ahead of Trump, and won by 4. And the vast majority of those caught committing fraud were Trump voters.
And, as Vacazar says, all the sensible reforms are blocked by the Republicans. (E.g., make election day a holiday, or even move it to a weekend). In Oz it's a weekend (and, BTW, mandatory -pay a fine if you don't vote - because the logic was make everyone vote you're a lot less likely to get extreme candidates, and you vote preferences). All the extreme measures are used by Rs to suppress the black/ D vote (e.g., in the white suburbs the wait to vote is measured in minutes, in the black inner city it is measured in hours. And that's why laws against giving a bottle of water to voters in queue was passed by Rs - it would make it more likely a black voter would say "fuck it" and go home and not vote after waiting 4 hours in queue. There are no such queues in the white areas). There is clear evidence the Rs studied how Ds vote and pass laws that disproportionately affect Ds (eg uni ID not acceptable ID but NRA membership card is acceptable).